The field of the invention is that of bottles and particularly bottles which may be made of polycarbonate or other plastic substances that may be stacked upon themselves.
Bottles have been used for many years to transport various fluids, the most important of which may be, quite naturally, water. While plastic bottles have been used for many years to package different types of fluids, until recently relatively large containers for water have been glass bottles of round configuration. Such glass bottles were relatively fragile and heavy, and susceptible to fracture into dangerous sharp fragments upon mishandling. The round shape of the bottle required the use of a packaging case for each bottle or an equivalent to stack the bottles for storage or shipment.
Recently, bottles used to transport, contain, and dispense liquids have been made from polycarbonate and other plastics. Such bottles are inexpensive, light, and safe in that they cannot break into dangerous shards when dropped. As with glass bottles, they do not contaminate or taint the liquids that they contain. In the main, plastic bottles have also been round in cross-section because that configuration presents the fewest number of stress points at which leaks might occur. For practical reasons plastic bottles have been relatively thin-walled with corrugations formed therein to provide strength and rigidity.
Recently plastic water bottles have been designed with a rectangular cross-section, and with parallel, relatively flat sides intended to mate with one another. Such bottles may be stacked one above the other. Because of the rectangular cross-section, theoretically no packaging or spacers are needed to support the bottles in proper alignment with respect to each other.
U.S. Pat. No. 4,308,955 to Schieser, et al. provides an example of a plastic rectangular cross-section parallel sided plastic or polycarbonate bottle intended to transport water. This bottle has horizontal reinforcing ribs and grooves formed in its sides. In addition, it has a tenon projecting from one of the parallel sides and a mortice formed in the mating parallel side. When such bottles are stacked on their sides one above the other, the tenon of one bottle can be inserted into the mortice of the immediately adjacent bottle so that the bottles interlock and form a stack.
The interfitting stackable bottles of Schieser, et al. have exhibited certain shortcomings. The horizontal pattern of ribs and grooves, which extend toward the bottom of the bottle, and the raised rib that surrounds the mortice in the female face of the bottle have been found to present stress points where cracks occur during use, with resulting breakage.
The technology of polycarbonate or other plastic parallel sided bottles offers great promise for producing light-weight, inexpensive, durable, and space-saving bottles. An object of the present invention is to provide an improved bottle which may be formed from polycarbonate or other plastics with improved resistance to cracking, leakage, and the like.